For Serbian language works, a 546 language note is routinely supplied because
it is necessary to designate the script of the work, since Serbian is commonly written in both the Cyrillic and roman alphabets. However, these notes are not routinely supplied for works in Croatian or Bosnian. Such a note for Serbian is normally formatted as below, if the note is only identifying Serbian as the language of an item:

546 In Serbian$b(Cyrillic).
546 In Serbian$b(roman).

However, if the identification of the alphabet does not end the field, then the tagging for the subfield is left off, e.g.